I am trying to get data on

I am trying to get data on the range of sales prices for "how-to" or technical guide-type apps. We are thinking about developing and marketing an interactive "how-to" app that will help individuals avoid the common mistakes made in pursuing the building related activities our company supports. We think the value will support a sale price between $3 and $7-- but have no data to support our decision. Please provide what data you have.